It is already known to support the filter belt by a metal or plastic screen belt permeable to liquids in gravity filtration through a filter belt. It is also known in vacuum filtering devices to guide the screen support belt with the filter belt on an arcuate path on the periphery of a drum through an angle of more than 180.degree. (see DE-AS No. 27 00 492). In the latter mentioned device the liquid is drawn off upwardly from the bottom area through the filter belt and the bottom area can rapidly become filled with solids and must be cleaned at short intervals in order to prevent the agglomerating solids from damaging the filter belt. The pure gravity filters have the disadvantage that the liquid to be filtered is only at a relatively low level above the supported filter, accordingly it penetrates the filter belt with low gravity pressure and for coping with large amounts of liquid throughput a correspondingly large and space occupying filter belt surface must be provided in the filtration area.